Mold for manufacturing electric discharge vessels



R. SCHARF NAGEL MOLD FOR MA NUFACTURING ELECTRIC DISCHARGE VESSELS- Original'Filed May 13-, 1938 2 Sheets-Sheet 1 L a L L by After/78y I 1943- R. SCHARFNAGEL 2,313,025 r MOLD FOR MANUFACTURING ELECTRIC DISCHARGE V ESSELS Original Filed May l3, 1938 2 Sheets-Sheet-2 I Ailarnex Patented Mar. 2, 1943 b Morin FOR MANUFACTURING ELECTRIC Y DISCHARGE VESSELS Rudolf Scharfnagel, Stuttgart, Germanyyvested in the Alien Prop 7 V Original application erty Custodian Mayj13, 1938, Serial No.

207,756. Dividedjand this application December 27, 1939, May 14, 1937 Serial No. 311,082. InGermanydivision of my copending No. 207,756, filed May 13,

This application'is a U. 8. application Serial 1938.

This invention relates to methods of manu facturing electric discharge vessels of the kind in which a disc-shaped member of ceramic or similar material is united with the bulb of the vessel by a glass seal arranged as'a coating on such Ceramic member, this member and seal forming a cover for the bulb. Preferably, such cover is used also to support the electrode system.

It has been customary to apply the glass in-: tended to form this seal to both the ceramic.

member and bulb at'the same time. Also iirhas been proposed to apply this glass to an insulating member, preferably of ceramic material, and.

simultaneously to apply it to an annular metal member arranged "to encircle such insulating member, and then to unite this metal member with the bulb.

It is the object 'of this invention to provide new and useful means for manufacturing discharge devices of the aforementioned kind.

My invention will be more readily understood from the following description taken in conjunction with the accompanying drawings, in which Fig. 1 is a somewhat diagrammatic sectional view of an electron tube of the type referred to by the invention, Fig. 2 is a fragmentary sectional view showing an example of a device for manufacturing one embodiment of the novel cover, Fig. 3 is a fragmentary sectional view illustrating an example of a device for manufacturing a second embodiment thereof, Fig. 4 is 'a fragmentary sectional view representing a second example of devices for manufacturing covers of the type shown in Fig. 2, Fig. 5 is an alternative form of a detail of the arrangement represented in Fig. 4, which issued as Patent No. 2,188,061, January 23, 1940.

The electron tube shown in example comprises a bulb A, an electrode system B, leads 6 joined to this system, and a cover composed of 'a ceramic disc-shaped member I and of a glass seal 5. Bulb A may be of a metal or of a suitable glass, and has a flange b to which seal 5 is fastened. Flange b is tapering toward its edge, being intended to be here of foil thickness, or nearly so. If the bulb A is of glass, flange b and seal 5 may be united with each other by the heat of a in the case of a metal bulb, preferably high frequency energy is employed for heating the bulb, thus securing flange b and seal 5 together. The

Fig. 1 by wayof gas jet, for instance, while c for the leads to pass through heating coils 4. Matrix I, 2 is heated frombelow, T as indicated by the arrows d, in order to melt latter operation may be effected by'the same high frequency coil that in a well known manner serves for outgassing the bulbA.

.For manufacturing the cover I, 5 the device represented in Fig. 2 may be used. This device comprises a die 3 and a matrix composedof the ceramic member-I itself and of a plate-shaped part 2 of iron in which member I-is seated.

Member I carries the leads 6. The die 3 has bores glass arranged thereon. This glass maybe in'a preheated condition or may be-poured on the matrix, thus being ,appliedthereto inliquid -dondition. By means of die 3 matrixil, 2 is moulded.to.;form a'pressed glass body 5 of disc shape. Part mic member I, however, is by die 3 caused to form a firmly interlocked structure with the glass body 5. Therefore, after removal of the die this structure I, 5 may be removed from matrix part 2 in order to be united with thebulb A of an electron tube in the manner described with referenceito Fig. 1.

Memberl may have bores e or recesses into which the material of body 5 may enter. 7 Such bores or recesses may be dispensed with if the porousness of the ceramic material is suflicient.

In the arrangement I, 2 is carried on a heating body 8 of iron provided with heating coils 'I. Part 2' does not stick toglass and is displaceable in a guide II so that it may be moved into the position shown in dotted lines. Die 3 is disposed in a guide 92 With part 2 in the position represented in full lines, this being the position of rest, there is a'hollow' space above member I. in diameter than die 3' and is 'to receive the glass from which the glass body 5 is'to be produced. The softened glass is in a first moulding operation pressed by die 3' against the ceramic member or matrix part I and thus caused to form therewith aflrmly interlocked structure in the same manner as described with reference to Fig. 2. Then matrix part 2' is raised into the dotteddine position while die 3' is 'still in its lower position. As a result, glass body 5 is formed with a tubular extension I2 by which it shall be fastened tube.

In the arrangement shown in Fig. 4 that part of the matrix to which glass doesnot stick is in' the nature of a metal chill 2" in which a glass 7 and is fitted with the melted glass" on N 2 is ofa material to t which the glass body 5 doesnot stick. 7 The cerashown in Fig. 3 the matrix This space is somewhat larger to the bulb of an electron i a disc is placed on the ceramic" member I in order to be united therewith by die 3". Member I is formed with a central tubular extension located in a central bore I8 of the: chill. An electric coil II serves to preheat the glass disc 5 and ceramic member I until the transformation temperature of the glass is reached, i. e., the lower limit of the destraining or release range decisive in member I enable the heat produced by jet I6 to act directly on the disc 5. The circumfer ential portion of disc 5 is protected from a harmful influence of the heat by the chill 2" which has a relatively large mass.' Air ducts g in the chill permit the gas jet IE to be suificiently fine.

Bore is is fitted with a lining ll of heat-proof insulating material, such as asbestos or clay. The chill is mounted on a table'IQ that can be raised or lowered by a suitable gearing 20 in order to adjust thev distance by'which member I is spaced from'the jet I6. Die 3" has pins I3 for producing bores in the glass body 5 in accordance with corresponding bores in member; I, while providing body 5 with a glass wart aroundeach such bore. In these bores the leads for the electrode system are: fixed after the assembly or or cover I, 5 has been removed from the chill. 1

If mass production is desired,-die 3" is replaced by the die 3A shown in'Fig. 5. Die 3A has the whereupon the cover I, 5, 6 may be at once removed from the chill. i In lieu oi a gas burner I5 an electric heating device may be employed whose heat radiation is concentrated toward the centre portion 01' memberI by means of a diaphragm.

The glass disc 5 instead of being supported by both member I and chill 2" may be held by member I alone, thus being out of contact with thechill. In the case represented, where disc I i is lying on the chill too, it is advisable to degas the metal from which the chill is to be made,

since otherwise air bubbles may form in thedisc 5.

I6 at once acts to unite the leads 5 with disc 5 dThe ceramic member I may be previously coated with glass.

What is claimed:is: An arrangement forpproducing a glass cover for an electric discharge vessel, which glass cover has a generally circular ceramic member and a glass body molded on said ceramic member and electrodes held in place in said ceramic member by said molded glassbody, said arrangement comprising a die, a heating portion made of metal which does not stick to glass, said heating porwhen placed upon said raised center portion, said i die containing bores ,for receiving said electrodes when said die'is lowered to mold the glass body and unite, it to the ceramic member. 7

RUDOLF SCHARFNAGEL. 

